Continued high caseload of rheumatic fever in western Pennsylvania: Possible rheumatogenic emm types of streptococcus pyogenes

ObjectiveTo evaluate the occurrence of cases of acute rheumatic fever (ARF) in western Pennsylvania although there has been a marked reduction of cases of ARF in the United States overall.Study designFrom 1994 to 2003, the cases of ARF evaluated at Children’s Hospital of Pittsburgh were reviewed. In addition, throat cultures were performed on a subset of these children and their family members beginning in 1995. Molecular typing was performed on isolates of the group A streptococcus (GAS) recovered, using field inversion gel electrophoresis (FIGE) and emm typing.ResultsThere were 121 new cases of ARF from 1994 to 2003. Of these, 57% were male. The median age was 10 years. The majority of children (57%) had carditis with or without another manifestation of ARF. The results of throat cultures were available for 231 persons; 36% (30/84) of the children with ARF and 14% (20/147) of family members were positive for GAS. Eight emm types were observed (emm 1, 2, 6, 12, 18, 28, 75, and 89). Data suggest that emm type 12 may be a rheumatogenic strain.ConclusionARF remains a problem in western Pennsylvania. Identification of emm types associated with cases should enlighten vaccine development.